What is Thin ?
Thin is a Ruby web server that glues together 3 of the best Ruby libraries in web history:
1.the Mongrel parser, the root of Mongrel speed and security
2.Event Machine, a network I/O library with extremely high scalability, performance and stability
3.Rack, a minimal interface between webservers and Ruby frameworks
More info: http://code.macournoyer.com/thin/

c:\railsproject\microposts>gem install thin
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed thin-1.5.0
1 gem installed
Installing ri documentation for thin-1.5.0...

# To run the thin server
c:\railsproject\microposts>rails server thin -p3005
C:/ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.5/lib/rack/handler/thin.rb:1:in `require': cannot load such file
        from C:/ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.5/lib/rack/handler/thin.rb:1:in `<top (required)>'
# However, there was an error occurred,
c:\railsproject\microposts>gem install eventmachine
Successfully installed eventmachine-1.0.0-x86-mingw32
1 gem installed
Installing ri documentation for eventmachine-1.0.0-x86-mingw32...
Installing RDoc documentation for eventmachine-1.0.0-x86-mingw32...
# Thats it!!! now, lets run again!
c:\railsproject\microposts>rails server thin -p3005
=> Booting Thin
=> Rails 3.2.11 application starting in development on
=> Call with -d to detach
=> Ctrl-C to shutdown server
>> Thin web server (v1.5.0 codename Knife)
>> Maximum connections set to 1024
>> Listening on, CTRL+C to stop